After learning that we no longer have that big old round electric oven (which would've made for a kickass set of resistors), i went into the kitchen to check what other rarely used appliance would do the job. The sandwich maker? Nah, i still use that. Besides, it doesn't look too easy to take apart. Oh wait, there's that flimsy toaster that i think i only used once, and i've never seen mom using it either. And it says 800 watts on the label. Oh my.
Taking it apart wasn't too easy because the materials used are so lame that the screws would spin freely but still hold the case into place. What do you expect from a $15 toaster. After removing the case, the control electronics are revealed. There's a HEF4066BP, a CD4541BE, three push buttons, 2 NPN transistors, a couple polyester caps, three LEDs, a 200k pot, a thermistor and a bunch of resistors. The PCB says T322-02 94V0 MADE BY HARVEST. I have no idea who this Harvest guy is. The power to this circuit is derived from a tap on one of the nichrome resistors that do the toasting.
On the power side there is a magnetic switch that holds the lever into place (that's why it only locks in the "down" position when it's plugged in). At this point i'm glad i took the thing apart because it's essentially one big fire risk. The enclosure is flimsy (at least they get credit for hooking it to the earth wire), the wiring is too thin, the switch is made by two fully exposed and rather lame looking copper strips, and best of the best: There is no fuse!!!
Maybe the power cord is meant to act as a fuse - i remember that the power plug on my old sandwich maker just melted one day.
Anyway. The three banks of resistors are in series and measure 66.6 ohms in all. And yes my meter reads 0.0 when shorted, and before you ask no they don't measure 22.2 ohms each because they're so sloppy, so it's quite a big coincidence. Evil toaster!
Now, applying Ohm's law and rounding a little bit, we do get 800 watts. However, anything that runs red hot is likely to have a strong positive tempco, so the resistance probably rises a fair bit in use thus power goes down. We'll see about that soon. Now i can test my +/-80v power supply and make toast at the same time.
And with all three banks in parallel i should get 7.4 ohms - just what i needed to test an audio amp.
Oh, one more thing. There's a cheap electrolytic on the power board. That i think gives you a good idea of this product's expected lifetime.
Taking it apart wasn't too easy because the materials used are so lame that the screws would spin freely but still hold the case into place. What do you expect from a $15 toaster. After removing the case, the control electronics are revealed. There's a HEF4066BP, a CD4541BE, three push buttons, 2 NPN transistors, a couple polyester caps, three LEDs, a 200k pot, a thermistor and a bunch of resistors. The PCB says T322-02 94V0 MADE BY HARVEST. I have no idea who this Harvest guy is. The power to this circuit is derived from a tap on one of the nichrome resistors that do the toasting.
On the power side there is a magnetic switch that holds the lever into place (that's why it only locks in the "down" position when it's plugged in). At this point i'm glad i took the thing apart because it's essentially one big fire risk. The enclosure is flimsy (at least they get credit for hooking it to the earth wire), the wiring is too thin, the switch is made by two fully exposed and rather lame looking copper strips, and best of the best: There is no fuse!!!
Maybe the power cord is meant to act as a fuse - i remember that the power plug on my old sandwich maker just melted one day.Anyway. The three banks of resistors are in series and measure 66.6 ohms in all. And yes my meter reads 0.0 when shorted, and before you ask no they don't measure 22.2 ohms each because they're so sloppy, so it's quite a big coincidence. Evil toaster!
Now, applying Ohm's law and rounding a little bit, we do get 800 watts. However, anything that runs red hot is likely to have a strong positive tempco, so the resistance probably rises a fair bit in use thus power goes down. We'll see about that soon. Now i can test my +/-80v power supply and make toast at the same time.
And with all three banks in parallel i should get 7.4 ohms - just what i needed to test an audio amp.Oh, one more thing. There's a cheap electrolytic on the power board. That i think gives you a good idea of this product's expected lifetime.
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